I. Field of the Invention
The present invention relates generally to medical devices and, more particularly, to a medical device to synchronize the activation of an imaging device, such as an X-ray machine, with the degree of patient inspiration.
II. Description of the Prior Art
In the operation of medical imaging devices, such as X-ray machines, it is highly desirable to obtain the image at a predefined degree of patient inspiration, at least where an image of the patient""s chest area is desired or upper airway films. In many cases, the image is desired at the full or maximum patient inhalation. However, in other cases, the image may be desired at complete exhalation or at some predefined point between complete exhalation and complete inhalation.
In many cases, the patient is merely instructed to either inhale or exhale to the desired degree of inspiration and then maintain that inhalation or exhalation while the image is taken. In other cases, however, the patient is either nonresponsive to commands either through illness or injury or because of the young age of the patient.
In this latter case, it has been the previous practice for the technician operating the imaging equipment to attempt to activate the imaging device at the desired degree of patient inspiration. This, however, has proven extremely difficult to accomplish, especially in the case of an infant patient due to the very high respiration rate of the infant. Consequently, when attempting to obtain an image from an infant at a predetermined degree of inspiration, for example maximum inhalation, it has been previously necessary to obtain multiple exposures from the imaging device of the infant in the hope that one of the multiple images will be either at or near the desired degree of inspiration.
The multiple exposure of patients and particularly infants to imaging devices such as X-ray machines is disadvantageous for two reasons. First, the use of multiple exposures to the X-ray machine in an attempt to obtain one good X-ray image is expensive not only in wasted X-ray film, but also technician time. Secondly, the exposure of the infant to multiple X-ray images necessarily increases the risk to the infant patient of cellular damage from the X-ray exposure.
The present invention provides a system which overcomes all of the above-mentioned disadvantages of the previously known devices.
In brief, the system of the present invention synchronizes the activation of an imaging device, such as an X-ray machine, with the patient""s respiration. The imaging device includes a trigger signal input for activating the imaging device in response to a preset signal. Such trigger signal inputs, furthermore, are conventional for imaging devices, such as X-ray machines.
The system of the present invention is used in conjunction with a respiration device which provides an output signal indicative of the degree of patient inspiration. Such a respiration device can comprise, for example, a ventilator or respirator band. In the case of a ventilator, ventilators conventionally provide a direct output signal indicative of the degree of patient inspiration. In the case of a respirator band, the respirator band conventionally includes control circuitry which likewise provides an output signal indicative of the degree of patient inspiration.
A control circuit means is then responsive to the output signal from the respiration device for generating the preset signal at a preselected degree of patient inspiration. The preset signal from the generating means is then connected to the trigger signal input of the imaging device in order to activate the imaging device. Preferably, the control circuit is both solid state based and electrically isolated from the patient.
In practice, the output signal from the respiration device is typically an analog signal. Assuming that the activation of the imaging device is desired at maximum patient inhalation, the control circuit generates the preset signal at maximum inhalation. The preset signal is, in turn, coupled to the trigger input of the imaging device in order to activate the imaging device.